Methods for making reinforced thermoplastic composites using reactive fibers and/or reactive flakes

ABSTRACT

Various methods and systems of making inorganic fiber/flake reinforced composites having a thermoplastic matrix are disclosed. The methods use systems similar to those used to make inorganic fiber/flake reinforced products having a thermoset matrix, but the systems and methods are modified to use thermoplastic precursor monomer(s) followed by in situ polymerization of the monomer(s) during and/or following forming of the desired shape of the products. These methods permit the manufacture of superior inorganic fiber reinforced thermoplastic matrix composites in large and very large shapes heretofore not possible, or practical.

BACKGROUND OF THE INVENTION

In the 1980's there was a mighty development effort by the automotivecompanies to replace many metal parts of vehicles with glass fiberreinforced composites (GFRC) to reduce weight and increase gas mileage.Some work was done with thermoplastics, but this was limited due to theextremely high tooling costs incurred for injection molding tooling, andbecause the viscosity of molten thermoplastics is too high forconventional forming processes used to make large and/or structural GFRCparts, such processes as RIM (Reactive Injection Molding), SRIM(Structural Reactive Injection Molding), RTM (Resin Transfer Molding),VARTM (Vacuum Assisted Resin Transfer Molding), SMC (Sheet MoldingCompound), BMC (Bulk Molding Compound), spray-up forming, filamentwinding, LFI (Long Fiber Injection molding) and pultrusion, much workwas being done on thermoset GFRC. In the injection molding processchopped glass fibers and pellets of a thermoplastic polymeric resin arefed into an extruder mix the two together at elevated temperature andmaceration due to the high viscosity of the molten thermoplasticpolymer(s) or copolymer(s). Substantial working and maceration isimportant and sometimes necessary to wet out the glass fibers at theelevated temperature due to the high viscosity, and as a result theglass fibers are shortened significantly. The resultant mixture isformed into a molding material that is supplied to a press or injectionmolding system to be formed with very expensive tooling into GFRC parts.During the extrusion process using single or twin-screw machines, theresin is melted and the fibres are dispersed throughout the molten resinto form a fibre/resin mixture. Next, the fibre/resin mixture may bedegassed, cooled, and formed into pellets. The dry fibre strand/resindispersion pellets are then fed to a moulding machine and formed intomoulded composite articles that have a substantially homogeneousdispersion of glass fibre strands throughout the composite article.Alternatively, in the process using continuous filaments, fibreglassfilaments are mixed with the molten resin in an extruder with the screwgeometry designed to mix the matrix with fibres without causingsignificant damage to the fibres. The resultant extruded mixtures arethen compression molded to form long-fibre reinforced thermoplasticparts having superior mechanical properties due to the nature of theorientation and the longer length of the fibers. Because of thesedifficulties, the use of thermoplastics to make vehicle parts was verylimited.

Therefore, much development work was being done and products were beingcommercialized using thermoset polymer chemistry and materials to makeGFRC. Much of this work came to naught because of recycling advantagesof metal parts versus thermoset GFRC parts. Metal parts can be remeltedat a cost advantage versus melt from iron ore, making scrap metalvaluable, but thermoset GFRC parts are not recyclable and no valuableuse for scrap thermoset GFRC parts could be found. Consequently, if asignificant portion of vehicles were to be made of thermoset GFRC, hugepiles of worthless and useless scrap would result along withunfavourable economics. Consequently, further GFRC penetration of theautomotive market slowed to almost a standstill, and even regressed insome applications.

With the newly proposed challenging CAFE gas mileage standards justintroduced, there is a larger than ever need for lighter weight vehicleparts which thermoplastic GFRC could satisfy, because thermoplastic GFRCscrap is recyclable. The thermoplastic polymers or copolymers can bemelted and reclaimed and ground thermoplastic GFRC can be used inconventional thermoplastic forming processes including injectionmolding, extrusion, etc. Thus, there is a larger than ever need to beable to make thermoplastic GFRC parts using thermoset processesincluding RIM, SRIM, RTM, VARTM, LFI, SMC, BMC, etc.

It is known to cast low viscosity caprolactam monomers, one containingan activator and another mixture containing a caprolactam monomer and acatalyst by mixing the two very low viscosity mixtures together prior tocasting. This mixture must be kept to less than about 100 degrees C. toprevent rapid polymerization, then, following casting, the cast mixtureis heated in the mold to cause anionic polymerization of the monomer toproduce a polyamide, but this method is not practical for most vehicleparts and many other current thermoset parts. If thermoplastic GFRC isto replace metals substantially in the automotive industry andelsewhere, economical method(s) must be found that will produce suchautomotive parts of equal or superior performance at competitive costswith metals. This is achieved with the methods of the invention.

SUMMARY OF THE INVENTION

The invention allows the processes used for making fiber and/or flakereinforced thermoset composites to be used to make fiber and/or flakereinforced thermoplastic composites. This is accomplished by combininglow viscosity mixtures of monomer(s) containing one or more catalystswith fibers and/or flakes having on their surfaces a chemical sizingcontaining one or more activators that upon contact with the catalyst(s)and mixture of one or more monomers and one or more activators and anelevated temperature, such as about 140 to about 200 degrees C., moretypically about 150 to about 180 degrees C. and most typically about 150to about 170 degrees C., causes anionic polymerization of at least about90 percent, typically more than 97 percent of the monomer(s) resultingin a similar percentage of polycrystalline polyamide or other polymer.Optionally, but typically, all of the fiber, and/or flake, and themonomer-activator mixture are preheated to or near the desiredpolymerization temperature. When molds are involved, it is typical, butnot necessary, that the molds also be preheated at least above themelting point of the monomer when the monomer is solid at roomtemperature. After forming, the composite, in or out of the mold, can beplaced in a hot environment to complete the polymerization to thedesired degree. The total polymerization time will depend upon thetemperature and degree of polymerization, but generally will requirefrom about 5 to about 15 minutes.

Methods of the invention include methods somewhat like, filamentwinding, pultrusion, spray-up, hand lay-up, RRIM, SRIM, RTM, VARTM, LFI,SMC, BMC and others, but modified according to the invention in waysdescribed in detail later, but in one or more ways that includepreheating the fibers and/or flakes, heating the monomer mixture in animpregnating container, preheating the monomer mixture, heating a mold,mandrel or form, and other equipment. The methods of the inventionpermit fiber loadings of up to 60 wt. percent or more, preferably up to50 wt. percent or more, much higher fiber loadings than existingthermoplastic composites. Because of the low viscosity of themonomer/catalyst mixture itself, compared to the typical viscosityranges of molten polymers in the typical thermoplastic compositemanufacturing processes, additional pigments, fillers, includingnano-size fillers, can be incorporated in the monomer mixture to achievedesired properties in the reinforced thermoplastic products of theinvention. Systems of the invention include systems somewhat like,filament winding, pultrusion, spray-up, hand lay-up, RRIM, SRIM, RTM,VARTM, LFI, SMC, BMC and others, but modified according to the inventionin ways described in detail later, but in ways that include one or morepieces of equipment to preheat the fibers and/or flakes, to heat themonomer mixture in an impregnating container, to preheat the monomermixture, to heat a mold, mandrel or form, and other equipment.

Mineral or other inorganic fibers and/or flakes, including glass fibresand/or flakes, are made by forming and attenuating inorganic moltenmaterial into fibers and/or flakes from a fiberizing bushing or orifice,with or without gaseous blasts to further attenuate the fibers andflakes to smaller diameters or thicknesses. Soft, plastic inorganicfibres, usually exiting tips or orifices in refractory metal containersfor the molten material, such as glass, are attenuated to the desireddiameter by jet blast of combustion gases or steam, by mechanical forcesexerted by melt spinning and/or by pulling cooled, solidified portionsof the fibers at speeds exceeding at least 1000 ft./min. using a winderor a chopper. Winders wrap the inorganic fibers into packages of directwound rovings, or provide strands of fibers that, after drying andcuring, are used to make up combined rovings or yarn containing a few ormany such strands.

Following attenuation of the plastic, inorganic fibers or flakes, wateris applied to the hot attenuated fibers and/or flakes to solidify andcool the fibers or flakes and then, conventionally, a chemical sizingcomposition, or chemical treatment, is applied to the surfaces of thefibres to protect the surfaces, to make the fibers easier to processinto packages or to chop, to bind the fibers together when dried to adesired degree, to cause a later applied polymer or copolymer matrixbetter coat the fibers and to provide a chemical linkage, bond, betweenthe surface of the fibers and the matrix polymer. After the fibres arecoated with the sizing, which is typically in aqueous form, they arefinished into reinforcing fiber products by either packaging wet orpartially drying and packaging in a still wet single end roving package,or fully drying and packaging as a single end roving, drying andcombining into a multi-end roving package, or chopping, and packaging ina wet state, or drying after chopping to form chopped fiber strands.Glass fibers are also conventionally made into mats including veil mats,chopped strand mats, nonwoven mats, yarn or roving reinforced nonwovenmats, and scrims, all made by well known dry and wet processes. Glassfiber products made by one or more of these methods are used in themethods of the invention. Other fibers are usable in the presentinvention including wollastonite fibers, ceramic fibers, fibers madefrom rocks such as basalt, fibers made from various slags, carbonfibers, carbon nanotubes, other inorganic nanotubes, and metal fibres.The reinforcement products and materials used in the invention will havea moisture content of no more than about 0.5 wt. percent, typically lessthan about 0.3 wt. percent and most typically less than about 0.2 wt.percent, often less than about 0.1 wt. percent.

Chemical sizings applied to the surfaces of the glass fibers typicallycontain a lubricant, a film former and a silane, but the film former isoptional for some products. The lubricant protects the surface of thefibers, essential to maximize the strength of the fibers, fromscratches, etc. caused by fiber-to-fiber rubbing abrasion and fromprocessing equipment. The silane acts as the chemical linking agent bybonding to the glass fiber and also to the polymer/copolymer matrix.Silanes containing organosilane groups are well known coupling agentsfor glass fibers and organic (e.g. polymer) phase, and serve tocovalently bond the organic groups in the compound to groups on theinorganic surfaces. The optional film former provides the desired degreeof bond between the fibers in the fiber strands to avoid fuzzing andexcess filamentation during processing in the fiber manufacturersoperations and/or in the composite manufacturers' operations. In theinvention the sizing also contains one or more ring-openingpolymerization activator substance, or a blocked precursor thereof, anda linking compound capable of linking the silane compound and theactivator substance. Examples of linking compounds are compoundscontaining alkyl, aryl, and alkyl-aryl groups that will causepolymerization of the hot catalyst-monomer mixture to form a polymermatrix around and bonded to the reinforcing glass fibers. Sizings can beapplied to flakes by spraying onto the flakes in a fluid bed or mixerand followed by drying.

The ring-opening polymerization activator may be any known organicreactive group that participates in a ring-opening polymerizationreaction, including anionic ring-opening polymerization, cationicring-opening polymerization and ring-opening metathesis polymerization(ROMP). The reactive groups may participate in the polymerization byforming a reactive center where further cyclic monomers can join afteropening to provide a larger polymer chain through ionic propagation. Ina preferred embodiment the activator is a group that serves the functionof an activator in the anionic ring-opening polymerization of a lactamor a lactone, e.g. the actiator can be an N-substituted imide group.Some examples of coupling activator compounds useful in the anionicring-opening polymerization of lactams include certainN-propylsilyl-W-acyl-ureas described in U.S. Pat. No. 4,697,009,incorporated by reference herein. In another embodiment, the couplingactivator compound is2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide, or similarcompounds, present in a range of about 1 to about 2.5 wt. percent of themonomer.

Such polymerizations are well-known in the art and are discussed morecompletely in U.S. Pat. Nos. 3,621,001; 4,188,478; 5,864,007; 6,579,965;and the patents cited therein, all of which are incorporated byreference herein. Generally, these polymerizations are conducted at lowtemperatures, 80-160° C. below the melting point of the resultingpolyamides (typically above 200° C.), and typically use, in addition tothe activator compound, two other ingredients; a lactam monomer and apolymerization catalyst. The monomer component may be a lactam orlactone having from 3 to 12 carbon atoms in the main ring, such ascaprolactam and caprolactone. The polymerization catalyst can be analkali metal salt of the lactam or lactone monomer, such as sodiumcaprolactam and sodium caprolactone. A catalyst like sodium caprolactampresent in the range of about 1.2 to about 3 wt. percent of the monomeris very suitable. There may also be other known auxiliary components inthe polymerization mixture such as co-initiators, catalysts,co-catalysts, electron donors, accelerators, sensitizers, processingaids, release agents, etc. Of course, the monomer(s) mixtures cancontain any of the known functional ingredients used in thermoplasticpolymers, including, but not limited to pigments, fillers, colorants,etc.

In the methods of the invention the resultant products can contain oneor more of wollastonite fibers, conventional pigments, fillers, andother additives by including such in the monomer mixtures. In additionto normal size parts made by existing methods for making reinforcedthermoplastic composites, very large products can be made using themethods of the invention, such as large body parts, floor pans andhigh-end thermoplastic composites for applications including windturbine blades, aircraft parts, automotive parts, pipe and reinforcedpressure vessels, tanks, etc.

Many types of polymers are formed in the present invention, mosttypically polymers formed by ring-opening polymerization reactionsincluding polyamides, including poly(caprolactam), commonly know as“Nylon-6” or “polyamide-6”. In the past the high viscosity of thepolyamides in the molten state prevented high glass fiber loadings inthe finished composites. The high viscosity of the molten polymers atprevious molding temperatures of 250-300 degrees C. prevented dispersionof the greater desired amount of glass fibers throughout the moltenresin without reducing the length of the fibers to a point where thereinforcement reaches diminishing returns in the processes of producingforming compounds for producing fiber reinforced composites. Thisproblem or barrier is overcome by the invention now that these polymerprecursors having low viscosities can be used in modified thermosetresin processes.

Anionic-catalysed ring-opening polymerization of lactams is a commercialmethod of preparing polyamide resins and such polymerization can beachieved at relatively low temperatures while under atmosphericpressures. Caprolactam is the most used lactam for these reactions andNylon-6 prepared by this method compares favorably in properties withthose prepared by conventional hydrolytic polymerization. The reactionkinetics, absence of by-products, and the crystalline nature of theNylon produced makes anionic polymerization of lactams a favourablemethod for several industrial applications, including the processes usedin the present invention. In one example, a silane-functionalizedisocyanate may be blocked with caprolactam to produce 2-oxo-N-(3(triethoxysilyl)propyl)azepane-1-carboxamide, which can participate inthe anionic ring-opening polymerization of caprolactam monomer. Suitableblocked precursors of suitable coupling activator compounds includeisocyanates blocked with compounds other than the activator compound.Under the processing conditions, such blocked isocyanate would becomeunblocked to furnish free isocyanate. The isocyanate, under the reactionconditions, becomes blocked with the monomer thus forming thepolymerisation activator. The silane functionality of the isocyanatecompound reacts with the fiber surfaces, such as glass fiber surfaces,producing interfacial adhesion.

According to the invention the activator can be in the chemical sizingon the reinforcing fibers and flakes and the catalyst can be mixed withthe monomer. For example, sized glass fibers can be mixed with a cyclicolefin monomer such as norbornene, and a polymerization catalyst to forma polymerization mixture that may then be exposed to conditionssufficient to cause an in situ ring-opening metathesis polymerization ofthe cyclic olefin monomer, i.e. in situ polymerization. The resultingcomposite product comprises a polymer matrix in which the glass fibersare grafted onto the polymer matrix with substantially improved couplingbetween the glass fibers and the polymer. This improved coupling shouldprovide tougher composite materials. Also, in one embodiment, the sizedglass substrate may be mixed with a lactam monomer, a caprolactam, and apolymerization catalyst to form a mixture that when exposed totemperatures in the ranges described above, cause in situ anionicring-opening polymerization of the lactam monomer. While not the mosttypical, the polymerization catalyst can be placed in the sizingcomposition and the activator for the monomer can be included in themonomer mixture to achieve polymerization when the sized fibers and/orflakes are combined with the monomer/activator mixture and subjected tothe polymerization temperature.

The methods of the invention produce reinforced thermoplastic compositeproducts having a far greater stiffness than existing reinforcedthermoplastic composite products and improved elevated temperatureperformance, such as in a temperature range of about 50 to about 80degrees C. Another advantage of the methods of the invention is that themolded products can be de-molded while still very hot, and also beforepolymerization is complete, and either cooled, or put into anenvironment at the polymerization temperature range until polymerizationis complete, followed by cooling. The maximum temperature, and time atpolymerization temperature, can be manipulated to control or tailor theproperties of the resulting products. Another advantage is that theproducts during molding and polymerization absorb less moisture due tothe high temperatures.

Products of the invention produced by the methods of the invention havepolymerization levels of greater than about 90 wt. percent, typicallygreater than about 93 wt. percent or 95 wt. percent, more typicallygreater than about 97 wt. percent and sometimes greater than about 98wt. percent. The degree of crystallinity is at least about 30 wt.percent, typically greater than about 35 wt. percent, often greater thanabout 40 or 43 wt. percent and sometimes greater than about 45 wt.percent. The melting point of the polyamide 6 polymer in the products ofthe invention is at least about 210 degrees C., typically above about212, more typically above about 215, often above about 217 and sometimesabove about 218 degrees C. The reinforced thermoplastic products of theinvention can also contain pigments, fillers, and other conventionaladditives by placing these ingredients in the monomer-catalyst mixtures,and/or the monomer-activator mixtures, used in the methods of theinvention.

When the word “about” is used herein it is meant that the amount orcondition it modifies can vary some beyond that stated so long as theadvantages of the invention are realized. Practically, there is rarelythe time or resources available to very precisely determine the limitsof all the parameters of one's invention because to do so would requirean effort far greater than can be justified at the time the invention isbeing developed to a commercial reality. The skilled artisan understandsthis and expects that the disclosed results of the invention mightextend, at least somewhat, beyond one or more of the limits disclosed.Later, having the benefit of the inventors' disclosure and understandingthe inventive concept and embodiments disclosed including the best modeknown to the inventor, the inventor and others can, without inventiveeffort, explore beyond the limits disclosed to determine if theinvention is realized beyond those limits and, when embodiments arefound to be without any unexpected characteristics, those embodimentsare within the meaning of the term “about” as used herein. It is notdifficult for the artisan or others to determine whether such anembodiment is either as expected or, because of either a break in thecontinuity of results or one or more features that are significantlybetter than reported by the inventor, is surprising and thus anunobvious teaching leading to a further advance in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front schematic of a modified pultrusion system according tothe invention.

FIG. 2 is a side schematic view of a modified filament winding systemaccording to the invention.

DETAILED DESCRIPTION

In the anionic ring-opening polymerization of the lactam or lactonemonomer, the combination of monomer and the catalyst produces acatalyzed monomer species containing an atom with a reactive free anion.Used herein, the term “ring-opening polymerization activator” is used todenote this catalyzed monomer species, and the term “ring-openingpolymerization activator compounds” may be defined as a group thatreacts with the catalyzed monomer molecule to cleave the lactam ring andstart the initial growth of the polymeric chain. In one embodiment thepolymerization catalyst may comprise an alkali metal salt of the lactamor lactone and the activator moiety may comprise an N-substituted imidegroup, e.g. an N-acyl lactam group. In another example, in thering-opening metathesis polymerization (ROMP) of a cyclic olefin monomersuch a norbornene, cyclopentadiene, cyclooctadiene, dicyclopentadiene,etc., the activator compound can be a cyclic olefin-substituted imidegroup that undergoes ROMP under catalytic conditions using a heavy metalalkylidene catalyst. In this example the activator becomes part of thepolymer chain.

The coupling activator compounds of the invention may be prepared inaccordance with the process set forth in the above mentionedincorporated U.S. Pat. No. 4,697,009, e.g. the coupling activatorcompounds may be prepared by mixing in an aprotic, polar organic solventsuch as N,N-dimethylformamide equimolar amounts of an alkali isocyanate(e.g. sodium isocyanate or potassium isocyanate), a 3-halopropyl silane(e.g. 3-chloropropyltriethoxysilane) and caprolactam, and reacting theingredients with each other at elevated temperature. At the end of thereaction and cooling the mixture to room temperature, the precipitatedalkali halide may be filtered off and the solvent may be removed fromthe filtrate to obtain the desired blocked isocyanate compound.Alternatively, coupling activator compounds may be prepared according tothe procedure describe in International Patent No. WO 2006/012957,incorporated herein by reference.

In another embodiment, the coupling activator,2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide may be preparedin accordance with the following reaction scheme A:

1.1 eq. of caprolactam (!) may be mixed with 1.0 eq. of3-isocyanatopropyltriethoxysilane (2) and the mixture heated at 80-100°C. until the completion of the reaction and formation of2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide (3). Thereaction progress can be measured by FT-IR, where disappearance of theisocyanate peak at 2300 cm⁻¹ should be observed. The reaction may be runneat or in solution, with 1,4-dioxane as the solvent. Organotin catalyst(e.g. dibutyltin dilaurate) may be used to significantly improve thereaction rate.

In one embodiment, a coupling activator compound of the invention may beused as the sole initiator in an anionic ring-opening polymerizationreaction, or may be used in combination with other known initiatorcompounds. For example, the carboxamide (3) activator compound above maybe used as the initiator in the reactive extrusion of Nylon-6 inaccordance with the following reaction scheme B:

In the above reaction, 97.5 wt % of caprolactam (1) may be mixed with1.0 wt % of 2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide (3).This mixture may be impregnated, coated, or otherwise brought intocontact with an array of fibers, such as glass fibers, sized with acomposition containing 1.5 wt % of a polymerization catalyst, sodiumcaprolactam (4), and then this impregnated fiber glass shape brought to,or maintained at, a temperature in the range of 80-205° C., moretypically within a range of about 140 to about 190 degrees C. for about4 to about 15 minutes to accomplish ring-opening polymerization andobtain a glass fiber reinforced thermoplastic product in which thematrix is

Nylon-6.

In another embodiment, a coupling activator compound of the inventionmay participate in a ROMP reaction such as shown in the followingreaction scheme C:

In this case, norbornene-substituted maleic anhydride (6) may be reactedwith γ-aminopropyltriethoxysilane (7) to provide a substituted imidecoupling activator compound (8). This coupling activator compound (8)can then undergo ring-opening metathesis polymerization (typically undercatalytic conditions using rhodium, rhenium, or molybdenum alkylidenecatalysts such as were developed by Grubbs or Schrock). Monomers such ascyclopentadiene, cyclooctadiene, dicyclopentadiene, norbornene or othermonomers suitable for ROMP may be used to yield polymers such ascompound (9).

In another embodiment, the invention uses a mineral or other inorganicfiber having bonded thereto a coupling activator compound of Formula Iabove. The inorganic substrate can be a plurality of glass fiberswherein at least most of the glass fibers are at least partially coatedwith the residue of a sizing composition comprising the couplingactivator compound. As previously described, the silane ingredient ofthe sizing covalently bonds to the glass fibers when the composition iscoated and dried on the glass fibers, attaching the coupling activatorcompound to the glass substrate. Glass fibers are particularly suitedfor reinforcing polyamide resins in the invention. Polyamide resinsreinforced with glass fibers include Nylon 6, Nylon 6:6, Nylon 6:12,Nylon 4:6, Nylon 6:10, Nylon 12, polyamide 6T (polyhexamethyleneterephthalamide), polyamide 6I (polyhexamethylene isophthalamide) ormixtures thereof. In one embodiment, the coupling activator compound maycomprise a blocked precursor of the active activator, e.g. a blockedisocyanate. In this embodiment, the precursor compound may be coated onthe glass substrate and the active form of the activator may begenerated in situ on the surface of a glass substrate when exposed tounblocking conditions. This process is illustrated by the reactionscheme D below:

The blocked isocyanate group can be obtained by reacting the isocyanategroup of the compound in reaction scheme A above with a compound thatrenders the isocyanate group unreactive. A suitable blocking agent forthe isocyanate group is determined by its ability to prevent the blockedisocyanate from reacting until a desired elevated temperature isachieved. Compounds that may be suitable blocking agents include, butare not limited to this list, oximes such as methyl ethyl ketoxime,acetone oxime, and cyclohexanone oxime, lactams such as ε-caprolactam,and pyrazoles. Organosilicon compounds with a blocked isocyanate groupare known in the art, e.g. see U.S. Patent Publication 2007/0123644,incorporated herein by reference. Upon heating or other deblockingconditions, these blocked isocyanates decompose to free isocyanate andthe blocking species. Deblocking temperatures depend on the blockinggroups and typically are in the range 70-200° C. The blocked isocyanatemay be included as a component of the sizing composition used to sizeglass fibres, and may be applied to glass fibres in the mannerpreviously described to form the entity identified as “blocked 2 onglass” in reaction scheme D above. When the glass fibres with blockedisocyanate compound are exposed to unblocking conditions, e.g. elevatedtemperatures during reactive extrusion of a glass-reinforced resin, theisocyanate group may become unblocked to form the active isocyanatecompound 2 chemically bonded to the glass surface. Once unblocked, theisocyanate group is available to react with the caprolactam monomer 1 inreaction scheme A above, thereby forming coupling activator compound 3bonded to the glass surface. The coupling activator compound may thenenter into the in situ polymerization reaction on the surface of theglass fibres in accordance with the invention. If the isocyanate isblocked with a monomer in the polymerization reaction; e.g. when theisocyanate is blocked by capolactam in the anionic ring-openingpolymerization of caprolactam, the blocked isocyanate may not need todissociate into the free isocyanate in order to facilitate thering-opening polymerization reaction.

Sizing compositions suitable for use on the fibers used in the presentinvention may be prepared by adding a coupling activator compound towater or other suitable solvent to form a solution. The sizingcomposition may also include other sizing composition components knownin the art, e.g. film-forming polymers, lubricants, defoamers, biocides,and silanes, etc. The sizing composition should contain an amount ofcoupling activator compound sufficient to accomplish the desiredparticipation in the ring-opening polymerization reaction with themonomer-catalyst mixture later. The overall concentration of thecoupling activator compound and other components in the sizingcomposition can be adjusted over a wide range according to the means ofapplication to be used, the character of the inorganic reinforcingfibers to be sized, and the intended use of the sized inorganicreinforcing material. In one embodiment, the sizing composition maycontain up to about 5 wt % of the coupling activator compound, based onthe solids content of the sizing. The components may be addedsequentially, or they may be pre-diluted before they are combined toform the sizing composition.

The sizing composition may be applied to the inorganic substrate bysuitable conventional methods in the art of making sized reinforcingfiber products. For example, the sizing composition may be applied toglass fibers pulled from a bushing using a standard kiss-rollapplicator. Other ways include contacting the glass fibers withdifferent static or dynamic applicators including a belt applicator,spraying, dipping, or any other known suitable means. Alternatively, thecoupling activator compound may be added to the binder used inconventional processes of forming woven or non-woven fibrous mats. Afterthe sizing has been applied, the fibers can be wound into rovingpackages, optionally dried, or can be chopped to form chopped fiberstrands. Rovings of sized continuous fiber strands may be used as is insome methods of the invention, or the rovings can be comingled and/orlater chopped to a desired length.

The length and diameter of the chopped glass fiber strands used in theinvention for reinforcing polyamide resins is determined by variousfactors such as, but not limited to, the ease of handling, andprocessing when the glass fibers impregnated with the polyamide resinprecursor mixture, the reinforcing effect of the glass fibres, theability to disperse the glass fibers, the type of polyamide resin inwhich the chopped glass fibre will be used to reinforce and the intendeduse of the molded glass-reinforced polyamide resin product. In someembodiments, the length of the chopped glass fibre strands is about 1.5mm and an upper limit of length of 75 mm or longer. In some embodiments,suitable for reinforcement of Nylon-6, the length of the chopped strandsis about 6 mm to about 25 mm. After the fiber strands have been chopped,they usually are dried to reduce the moisture level of the fibers to alow level, e.g. below 0.1-0.5%. The average diameter of the fibers usedin the invention will vary based on the particular forming method beingused, but can range from sub-micron to about 30 microns, but typicallywill range from about 8 to about 23 microns and more typically fromabout 9 to about 20 microns. For chopped fiber strands the averagediameter for many products will range from about 10 to about 17 micronsand the rovings will normally contain fibers having average diameters inthis range and up to the 23-30 micron size.

Non-limiting examples of glass fibres suitable for use in the inventioninclude, but are not limited to, fiberizable glass compositionsincluding “E-glass”, “A-glass”, “C-glass”, “S-glass”, “ECR-glass”(corrosion resistant glass), “R glass”, “T-glass”, and fluorine and/orboron-free derivatives thereof. Typical formulations of glass fibres aredisclosed in K. Lowenstein, The Manufacturing Technology of ContinuousGlass Fibres (Third Ed. 1993), incorporated herein by reference.

The invention provides systems and processes for making reinforcedthermoplastic resin products, and the products so produced, usingmineral and/or inorganic fibers that have bonded thereto one or morecoupling activator compounds according to of the present invention. Inone embodiment, a sizing composition comprising the coupling activatorcompound of Formula I above may be applied to glass fibers, the sizedglass fibers then are brought into contact with a mixture of lactammonomer and a polymerization catalyst to form a molded product and themolded product is exposed to conditions, such as elevated temperatureand time, sufficient to cause an in situ anionic ring-openingpolymerization of the lactam monomer, forming a polymer/glass fibermatrix in which the glass fiber is grafted to the polyamide polymer. Thepolymerization is referred to as “in situ” because the polymer is formeddirectly on the surface of the glass fibers, versus the prior artmethods of first forming the polymer(s) or copolymer(s) and then coatingthem onto the glass fiber surfaces. As a result, the coupling of theglass fibers and the polymer matrix of the composite material issubstantially improved over prior art glass-reinforcedpolymers/copolymers.

Fiber reinforced thermoplastic polymer products of the invention areproduced using unique, novel modifications of well-known forming methodsused to make fiber reinforced thermoset matrix composites includingpultrusion, filament winding, SRIM, resin transfer molding, andreinforced reaction injection molding (RRIM), vacuum assisted resintransfer molding (VARTM), long fiber injection molding (LFI), sheetmolding compounds (SMC), bulk molding compound molding (BMC), spray up,hand lay up, and others. The examples below illustrate the production ofglass fiber-reinforced polyamide-6 using such processes of theinvention.

EXAMPLE 1

Referring to FIG. 1, continuous, dry glass fiber strands 10, the glassfibers in the strands 10 having been previously sized with a sizingcomposition comprising an amount of2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide (compound 3 inreaction scheme A above) within the suitable range disclosed above, aconventional amount of any conventional organosilane normally used inglass fiber sizings, and a conventional amount of one or moreconventional glass fiber lubricants conventionally used in glass fibersizings, are pulled from a plurality of roving packages on racks (notshown) by the puller in the process. The glass fibers in this exampleare E glass fibers having an average diameter of about 20 micron. Theglass fiber strands 10 are pulled over a multi-grooved guide roll 12supported on a free wheeling mandrel 14 with one or more strands 10being in each groove to spread out the strands 10 into a horizontalarray 16 suitable for impregnation with a monomer-catalyst mixture. Thestrand array 16 is then passed over the top of a multi-grooved roll 18similar or like the multi-grooved roll 14, also supported by afree-wheeling mandrel 20 and then the strand array 16 is pulled into acontainer 21. Optionally the fiber strand array 16 can be preheated bypassing through an optional oven 19 to preheat the fibers to at least100 degrees C. or higher, up to a temperature in the range of about 120to about 190 degrees C. before entering the container 21. The container21 is optionally heated and receives a monomer mix 22, preferablypreheated, to at least 100 degrees C. or higher, up to a temperature inthe range of about 120 to about 140-190 degrees C. before entering thecontainer 21. The monomer mix 22A comprising caprolactam monomer 1 andsodium caprolactam catalyst 4, as shown in reaction scheme B above. Thetemperature of monomer mix 22A in the container 21 is maintained orfurther heated in the container 21 with conventional heating means to atemperature of at least about 100 degrees C. and up to about 130 toabout 140-190 degrees C. No detrimental amount of polymerization of themonomer will take place or build up in the container 21 because anypolymerization of the monomer will be with the activator on the fibersand will be removed from the container 21 with fully coated fiberstrands 25. The resultant very low viscosity heated monomer mixture 22will rapidly impregnate the strands 10 and coat the fibers in thestrands 10 with the monomer mixture 22 to form partially coated fiberstrands 23 that can be pulled against one or more rods 24 in thecontainer of monomer mixture 22 to spread out the fibers in thepartially coated fiber strands 23 and to produce the fully coated fiberstrands 25. The fully coated fiber strands 25 are then pulled out of theheated monomer mixture 22 by pulling them over a rod 26 after which theyare pulled into and through a mold 28 having a tunnel profile accordingto the desired cross section profile of the molded product. At least anupstream length section 28 A of the mold 28 is maintained at atemperature in the range of about 150 to about 190 degrees C. and issufficiently long such that the conditions within at least an exteriorportion comprising a plurality of the fully coated fiber strands 25reach a completion of an anionic ring-opening polymerization of thecaprolactam 1 in accordance with reaction scheme B, normally requiringabout 5-15 minutes.

A resulting glass-reinforced Nylon-6 interim product 30 is then pulledfrom the mold 28 with opposed driven pulling rollers 32 and 34 mountedon axles 33 and 36 respectively. These driven pulling rollers 32,34provide the pulling force for the entire process. Optionally, a finallength section 29 of the mold 28 can be cooled to a temperature suchthat an exterior portion of the interim product 30 has stiffer surfacesfor the driven puller rolls 32,34 to pull against. The interim product30 is then cut into desired lengths using a conventional rotating sawblade 38 mounted on a driven axle 37, or with other conventional cuttingdevices, to form fiber reinforced Nylon-6 products 39. If necessary, ordesired, the products 39 can be further processed in a conventional oven(not shown) to complete the polymerization of any monomer mixture in theinterior portion of the product 39, and/or in a conventional coolingchamber (not shown) to cool the product 39 to a desired temperature.Alternatively, the cutting of the interim product 30, such as with thecut off rotating saw blade 38, can be conducted following the finalheating and/or cooling steps. Thus, any profile shape and lengthnormally made using the pultrusion process conventionally used to makefiber reinforced thermoset polymer/resin products can according to theinvention now be used to make fiber reinforced thermoplastic products inwhich at least about 90 percent of the precursor monomer is polymerizedin the pultrusion process.

EXAMPLE 2

This example illustrates the production of a glass fiber-reinforcedpolyamide-6 using a modified, according to the invention, resin transfermolding (RTM) process or a modified, according to the invention,reinforced reaction injection molding (RRIM) process. A glass fiberpreform is made, having or approximating the shape of the desiredproduct, at least in two dimensions, using any conventional mannerexcept that the glass fibers in the glass fiber strands used in theglass fiber products making up the preform, chopped and/or continuousfiber strands, have been sized with a sizing composition comprising asufficient amount of2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide, or othersuitable silane coupling agent, 0-70 wt % of a polyurethane emulsion ora suitable mixture of emulsions, 10-50 wt % of a lubricant or mixture oflubricants, and optionally, 0-50 wt % of any other conventional requiredor desired additives. By sufficient amount is meant an amount that willpolymerize at least 90 wt. percent of one or more thermoplasticprecursor monomers that will later coat the fibers and become the matrixaround the fibers.

The preforms can be made with conventional hand lay up, wet forming, dryforming, and thermoforming process. The preforms can contain one or morelayers of chopped fiber strands, woven fiber fabric, chopped strand mat,continuous strand mat, woven or nonwoven scrim, nonwoven fiber mat, andveil mat products, formed or cut to the shape of the cross section ofthe desired product. As mentioned above, when one or more components ofthe preform contains a binder bonding the fibers or strands of fiberstogether, the activator compound can be in the binder instead of in thesizing on the fibers and/or flakes. In an alternative modified processdisclosed below, it is not necessary to have an activator compound onthe fibers and/or flakes.

In the modified methods used in the invention the preform, preferablyheated to at least 100 degrees C. and up to about 200 degrees C., butbelow the temperature that will cause deterioration of the sizing, isthen placed into a mold, normally a metal mold, and preferably apreheated to a similar temperature or a temperature below about 190degrees C. The mold has removable top and bottom sections. The topsection is placed appropriately to form the top of the mold and the topand bottom sections are locked, or otherwise secured tightly, to themold periphery (sides). The upper part of the mold might be replaced bya vacuum bag where vacuum assisted resin transfer molding (VARTM) isused. The mold will have one or more valved injection ports in desiredlocations in the periphery, sometimes in the top and/or bottom sections.The mold and the fiber perform are then, if necessary, further heated toa temperature in the range of about 140 to about 200 degrees C., usuallyby using a cartridge heater or with heated oil in cavities within themold parts or in an oven, and a monomer-catalyst mixture, like that usedin Example 1 above, preferably preheated to at least about 100 degreesC. and up to about 190 degrees C., but below a temperature that wouldcause deterioration of the mixture, is injected under conventionalpressure rapidly into the mold surrounding the perform. Air in the moldand perform is vented out of the mold with conventional vents, or themold can be evacuated using a partial vacuum if desired, prior to theinjection step. As soon as the mold is fully filled as indicated byreaching a desired pressure in the mold, a pressure within the range ofabout 1 to about 30 bars, more typically within the range of about 3 toabout 1-5 bars for low density products and about 5-30 bars for higherdensity products and/or larger products, the injection ports are shutand the heated filled mold is maintained at a temperature of at leastabout 150 degrees C. for a time that will produce at least about 90percent polymerization of the monomer into Nylon-6, usually about 7 toabout 12-15 minutes, or alternatively, for a shorter time sufficient toproduce sufficient polymerization that the hot product can be removedfrom the mold without the product deforming during remainingpolymerization to at least 90 percent polymerization. De-molding canoccur while hot and the molded reinforced thermoplastic Nylon-6 can beremoved and either maintained at temperature to complete polymerizationand cooled, or if desirably polymerized, cooled to produce the product.No detrimental polymerization takes place in the monomer/catalyst mixprior to injection. A simple one-tank injection system could be used. Noadditional mixing heat, typically used in thermoset systems, isnecessary in the method of the invention, therefore no cleaning of thesystem parts caused by mixing heat in the prior art processes isrequired here.

In this method, the products can contain one or more of wollastonitefibers, conventional pigments, fillers, and other additives by includingsuch in the monomer mixtures. Very large products can be made usingthese methods of the invention, such as large body parts, floor pans andhigh-end thermoplastic composites for applications such as wind turbineblades, aircraft parts, and reinforced pressure vessels

EXAMPLE 3

Reinforced thermoplastic composite products can also be made usingmodified BMC processes. In this method, the thermoplastic precursormonomer(s), such as a lactam monomer, and one or more catalyst compoundsas disclosed above, is heated to temperature range above the meltingpoint of the monomer(s) and below the reaction temperature of thepolymerization and placed into a BMC type or any mechanical mixer thatcan, optionally, also be heated or cooled. While the mixer is turning,reinforcement in the form of one or more of fibers, flakes and choppedstrands of fibers, the fibers or flakes having on their surfaces one ormore of the activator compounds, such as that used in Example 1, isslowly added to the monomer mixture while mixing until all reinforcementis added and thoroughly dispersed in the monomer mixture, to form a BMCcompound. If desired, the temperature of this mixture can be maintainedat the temperature of the monomer/catalyst mixture using eitherpreheated reinforcements or a conventional heating BMC mixer. This BMCcompound can then be extruded and cut into slugs, or removed and dividedinto desired weights for making desired products, all the timemaintaining the temperature low enough that significant polymerizationdoes not occur, except that it may be desirable to cause a small amountof polymerization to take place during mixing and/or extrusion to raisethe viscosity of the BMC compound to make it easier to divide andhandle.

The resultant slugs of cooled BMC are then molded using a conventionalpress suitable for molding BMC compounds at high pressure while the BMCcompound of the invention is in heated matched metal molds and/or dies,the temperature of the mold and/or dies being sufficient to rapidly heatthe BMC compound to a temperature in the range of about 140 to about 190degrees C. The pressure and temperature on the formed BMC compound ismaintained for about 5 to about 15 minutes to achieve at least 90percent polymerization of the monomer(s) after which the formed productcan be de-molded hot, or cooled somewhat in the mold before de-molding.Alternatively, the time in the mold can be reduced by polymerizing onlythe outer portion of the molded shape to at least 90 percent to form aninterim product, de-molding and putting the partially polymerizedinterim product into an oven to complete the polymerization. Theresultant reinforced thermoplastic composite products are superior toconventional injection molded reinforced thermoplastic parts because thereinforcement in the parts are larger, i.e. have been reduced in size orlength or both by this modified BMC method than by the compoundingnecessary for making injection molded parts. Also, the cost of theequipment for this method of the invention is substantially less thanthe cost of equipment needed for conventional injection moldingprocesses.

EXAMPLE 4

Other methods of the invention are modified sheet molding compound (SMC)methods. Two modified methods are suitable. In the first method, one ormore layers of fiber reinforcement products including woven roving oryarn fabric and/or scrim, chopped strand mat, continuous strand mat,nonwoven mat, chopped rovings, chopped strands of fiber, choppedfilaments, and veil mat in any desired combination are impregnated andcoated with the monomer mixture like used in Example 3, or optionally acool monomer mixture also containing one or more activator compounds,using normal SMC impregnation techniques, except that in this method theviscosity of the monomer mixture often is lower. When the monomermixture contains only monomer and a catalyst, the sizing on thereinforcement fibers, or the binder bonding the fibers together in themat(s) will contain the appropriate amount of one or more activatorcompounds. If it is desired to delay polymerization until the resultantSMC compound is cut and shaped into a desired product in a heated moldand press similar to that disclosed in Example 3, the impregnated SMC iscooled and/or maintained at a temperature below that where significantpolymerization of the monomer will take place, at least after a smallamount of polymerization has occurred to stiffen up the matrix, untilthe cut SMC pieces of this method are in the heated mold.

When it is desired to complete the polymerization to at least 90 percenton the modified SMC line, it is desirable that the activator compound(s)be on the surface of the fibers or in the binder bonding the fibersand/or the strands of fiber together. In this option, the monomermixture is heated to at least 100 degrees C. prior to impregnation, andmore typically, to a temperature in the range of 130 to about 150degrees C. or higher prior to impregnation. Following or even duringimpregnation, the resulting sheet is carried through an oven topolymerize the monomer(s) in the matrix of the sheet to at least about90 percent to form a hot, reinforced thermoplastic composite sheet. Thishot sheet can either be heated further to a thermoformable temperature,in or prior to molding, and thermoformed into the desired shape anddensity. Alternatively, the hot reinforced thermoplastic composite sheetcan be cooled and used as is for many applications, or can be shipped toa molding customer where it can be reheated to a thermoformabletemperature and thermoformed into the desired shapes.

Optionally, any of the above methods can include running thereinforcements through an oven to heat the reinforcements to atemperature of at least 100 and up to about 130 degrees C., and moretypically to a temperature in the range of above about 130 and up toabout 200 degrees C. prior to the impregnation step. This optional stepwill speed the polymerization of the monomer matrix and also can shortenthe length of the production line because the reinforcement can beheated faster before it is impregnated and coated with the monomermixture.

EXAMPLE 5

The invention also includes modified filament winding methods for makingreinforced thermoplastic composite products. FIG. 2, a front schematicview of a typical filament winding system, will be used to describe themodified methods of the invention. Continuous, dry glass fiber strandsand/or strips of woven or nonwoven mat, fabric or scrim 40 are pulledfrom a plurality of roving packages on racks (not shown) and/or fromrolls supported on rotating mandrels (not shown) by the puller in theprocess, a rotating mandrel 62 and forming product 66 to be described inmore detail later. The glass fibers in the strands and/or strips 40would have usually been previously sized, or bonded together, with asizing or binder composition comprising an amount of2-oxo-N-(3-(triethoxysilyl)propyl)azepane-1-carboxamide (compound 3 inreaction scheme A above) within the suitable range disclosed above, anda conventional amount of one or more conventional glass fiber lubricantsconventionally used in glass fiber sizings, The glass fibers in thisexample are E glass fibers having an average diameter in the range ofabout 8 to about 23 microns. The glass fiber rovings or strands/strip(s)40 are pulled over a multi-grooved guide roll 42 supported on a freewheeling mandrel 44 with one or more strands/strips 40 being in eachgroove of the grooved roller 42 to spread out the strands/strips 40 intoa horizontal array 46 suitable for impregnation with a monomer-catalystmixture. The strand array 46 is then passed over the top of anothermulti-grooved roll 48 similar or like the multi-grooved roll 44, alsosupported by a free-wheeling mandrel 49 and then the strand array 46 ispulled into a container 53. Optionally the fiber strand array 46 can bepreheated by passing through an optional oven 50 to preheat the fibersto at least 100 degrees C. or higher, up to about 170-200 degrees C. toproduce heated glass fibers/strip(s) 51, before entering the container53.

The container 53 is optionally heated and contains a monomer mixcomprising caprolactam monomer 1 and sodium caprolactam catalyst 4, asshown in reaction scheme B above. This monomer mix 55 can preferably bepreheated prior to entering the container 53, and maintained at theentering temperature or further heated in the container 53 withconventional heating means to a temperature of at least about 100degrees C. and up to about 130 to about 140 degrees C., No detrimentalamount of polymerization buildup will occur in the container 53 andresident monomer mixture 55 of the monomer because any polymerizationthat does occur in the container 53 will take place on the fibers andwill be carried out of the container 53 with fully coated fiber strands59. This resultant very low viscosity heated monomer mixture 55A willrapidly impregnate the strands/strip(s) 46 or heated strands/strip(s) 51and coat the fibers in the strands/strip(s) 46 with the monomer mixture55 to form partially coated fibers 56 that can be pulled against one ormore rods 57 in the container of monomer mixture 55 to spread out thepartially coated glass fibers 56 in the strands 46 or 51 and to producefully coated fibers in the fiber strands/strip(s) 59.

The fully coated fiber strands/strip(s) 59 are then pulled out of theheated monomer mixture 55 by pulling them over a rod 60 after which theyare pulled onto a rotating mandrel or form 62, preferably heated to atemperature in the range of about 150 to about 190 degrees C. with anysuitable heating method. The rotating mandrel or form 62 is supportedand driven by driven rotating supports 64, one of such supports 64connected to each end of the mandrel or form 62 at its horizontal axis.Rapid polymerization can begin as soon as the heated and fully coatedfiber strands/strip(s) 59 contact a rotating heated mandrel or form 62,or previously laid down material 66 heated by the heated mandrel or form62. Alternatively, or in addition, when formation of the desired shapeis completed, the entire mandrel or form 62 and/or formed product can beremoved from the supports 64, or from the mandrel or form 62 and placedin a hot oven to complete the polymerization to a point where at least90 percent of the monomer has been polymerized. Completion of theanionic ring-opening polymerization of the caprolactam 1 in accordancewith reaction scheme B, normally requires about 5-15 minutes at theabove described rapid polymerization temperature range. Instead of, orin addition to, internal heaters for heating the mandrel or form 62, oneor more external heaters 65, such as convection heaters, radiationheater(s), IR heaters, can be spaced from portions, or most of, themandrel or form 62 and the interim product 66. In the above-describedsystem, all of the elements 42 through 60 normally shuttle back andforth along the length of the mandrel or form 62 at a desired speed toproduce a desired pattern of fiber strands/strip(s) in the formed glassfiber reinforced Nylon-6 product.

Using this method of the invention, very large, continuous glass fiberreinforced thermoplastic pipes, tanks, or other hollow shapes can, forthe first time be rapidly made at a relatively low cost and superiorquality compared to previous methods.

EXAMPLE 6

In this method, fiber rovings, more typically glass fiber rovings, arefed to spray up equipment including a roving chopper, the fibers havinga sizing on their surfaces containing one or more activator compoundsand in amounts, as described above, and a monomer/catalyst(s) mixture asused in one or more of the above Examples is sprayed onto thereinforcing fibers of the chopped rovings from one or a plurality ofspray nozzles. The monomer(s) mixture is heated to a temperature of atleast about 100 degrees C. and up to a temperature of 200 degrees C.,more typically in a range of about 100 to about 190 degrees C. beforebeing sprayed onto the chopped rovings and the so coated chopped rovingsare directed onto a mold element or earlier applied coated choppedrovings. After molding is completed or during molding and after moldingis completed, the monomer mixture coated chopped rovings are heated to atemperature in the range of about 140 to about 190 degrees C. topolymerize at least about 90 percent of the monomer(s) to produce afiber reinforced thermoplastic composite. The mold element canoptionally be heated to a temperature in the range of about 100 to about190 degrees C. before the first monomer coated chopped rovings aresprayed onto the mold element.

Instead of heating the reinforcement and/or monomer(s) mixture to atemperature above about 100-130 degrees C. during and/or after themixture of these materials are building up on the mold element, theresulting built up interim product can be cooled to solidify themonomer(s) mixture to give the interim product rigidity and strengthsufficient to remove a perform product from the mold element and tohandle it to place it into a matched metal mold preheated to atemperature in the range of about 140 to about 190 degrees C. afterwhich the perform is pressed and heated to the temperature range of thepreheated mold while under a high pressure of at least about 5 bars todensify the perform and form the desired shape until at least sufficientmonomer(s) in the exterior portion of the shape has polymerizedsufficiently to maintain the desired shape after de-molding, or until atleast about 90 percent of the monomer(s) have been polymerized. Afterde-molding, the partially polymerized shape is maintained at atemperature in the range of about 140 to about 190 degrees C. until atleast about 90 percent of the monomer(s) has polymerized.

Very large and complex shapes including hot tubs, bath tubs, showerstalls, boat parts, and the like can be made using this method.

EXAMPLE 7

The conventional long fiber injection molding process combines a resinwith long fibers in a mixing head and then injects this mixture into amatched metal mold under high pressure. When using thermoplastic resins,the high viscosity of the molten thermoplastic polymer inhibits thoroughcoating of the long reinforcing fibers and/or slows the mixing andmolding cycle substantially. In this method of the invention, amonomer/catalyst mixture of the type disclosed above in Example 2 isheated to a temperature of at least 100 degrees C. and up to about140-150 degrees C. prior to entering the mixing head, and long inorganicfibers, more typically glass fibers, have on their surfaces a sizingcontaining an activator of the type used in Example 2. Optionally theinorganic fibers can be preheated to a temperature of at least about 100degrees C. and up to about 140-150 degrees C. prior to being contactedwith the heated monomer mixture. Because of the low viscosity of themonomer mixture, it can also contain one or more pigments, fillers,colorants, or other desired ingredients.

The monomer mixture impregnated long inorganic fibers are then injectedunder high pressure into a matched metal mold to produce a desiredshape. Optionally the mold is heated to a temperature in the range ofabout 130 to about 190 degrees C. to begin polymerizing the monomer(s)that are against the heated mold surface and in the outer shell of theformed shape. The mold is then shuttled into a press to polymerize underpressure and the desired temperature. The desired shape is de-moldedeither after sufficient polymerization has taken place that thede-molded shape is stable, or after at least 90 percent of themonomer(s) have been polymerized. In the option of early de-molding, thede-molded shape is maintained in an environment of at least about 130 toabout 190 degrees C. until the at least about 90 percent polymerizationis complete. Advantages of this method of the invention is that themixing head does not have to be cleaned very often and that manydifferent kinds of reinforced thermoplastic polymers can be produced,including Nylon-6 and Nylon-66.

The advantages in addition to those mentioned above will be obvious tothose of ordinary skill in the art, e.g. the substantially lower moldingtemperatures compared to the molding of molten thermoplasticpolymers/copolymers, and the substantially lower equipment and operatingcosts resulting. Also, different embodiments employing the concept andteachings of the invention will be apparent and obvious to those ofordinary skill in this art and these embodiments are likewise intendedto be within the scope of the claims. The inventor does not intend toabandon any disclosed inventions that are reasonably disclosed but donot appear to be literally claimed below, but rather intends thoseembodiments to be included in the broad claims either literally or asequivalents to the embodiments that are literally included.

The invention claimed is:
 1. A method of making a reinforcedthermoplastic composite product comprising; a) preparing a monomermixture containing one or more thermoplastic precursor monomers and oneor more catalyst compounds, the monomer mixture containing no activatorcompounds, this mixture being such that when brought into contact withone or more inorganic reinforcing materials having one or more activatorcompounds on surfaces of the one or more reinforcement materials, saidactivator compound(s) being a material that will react with the monomermixture to cause polymerization of the one or more monomers when in thetemperature range of about 140 to about 200 degrees C. to produce athermoplastic matrix, b) heating the one or more reinforcing materialsto a temperature of at least about 130 degrees C., and/or c) heating themonomer mixture of step a) to a temperature of at least about 100degrees C., and/or d) optionally heating a mold element, in which thepolymerization of the monomer(s) will take place, to a temperature inthe range of about 130 to about 200 degrees C., e) coating the surfacesof the one or more reinforcing materials having on their surfaces adried coating of a size composition containing the one or more of saidone or more activator compounds, with the monomer mixture of step a)prior to contact with the optionally heated mold element, f) bringingthe monomer mixture coated reinforcing materials into contact with, theoptionally heated mold element to form a desired shape of the dried sizecoated and the monomer mixture of step a) coated reinforcing materials,the monomer mixture of step a) forming a matrix around the reinforcingmaterials, and g) heating or maintaining the temperature of the desiredshape in a range of about 140 to about 190 degrees C. until at leastabout 90 percent of the one or more monomers in an exterior portion ofthe desired shape have polymerized to one or more thermoplasticpolymers.
 2. The method of claim 1 wherein the monomer(s) mixture isheated prior to the coating of the reinforcement with the monomer(s)mixture.
 3. The method of claim 1 wherein the reinforcement is heatedprior to coating with the monomer(s) mixture.
 4. The method of claim 1wherein both the reinforcement and the monomer(s) mixture are heated toa temperature above about 130 degrees C. prior to coating of thereinforcements with the monomer(s) mixture.
 5. The method of claim 1wherein said activator compound(s) is/are compound(m)that initiate aring opening polymerization of the one or more monomers.
 6. The methodof claim 2 wherein said activator compound(s) is/are compound(s) thatinitiate a ring opening polymerization of the one or more monomers. 7.The method of claim 4 wherein said activator compound(s) is/arecompound(s) that initiate a ring opening polymerization of the one ormore monomers.
 8. The method of claim 3 wherein said activatorcompound(s) is/are compound(s) that initiate a ring openingpolymerization of the one or more monomers.
 9. The method of claim 1wherein the monomer(s) are comprised of a lactam monomer, a caprolactammonomer, a lactone monomer or mixtures of two or more of these monomers.10. The method of claim 2 wherein the monomer(s) are comprised of alactam monomer, a caprolactam monomer, a lactone monomer or mixtures oftwo or more of these monomers.
 11. The method of claim 1 wherein thereinforcement comprises one or more of inorganic fibers, strands offibers, and flake.
 12. The method of claim 10 wherein the reinforcementcomprises glass fibers and/or strands of glass fibers.
 13. The method ofclaim 6 wherein the reinforcement comprises glass fibers and/or strandsof glass fibers.
 14. The method of claim 7 wherein the reinforcementcomprises glass fibers and/or strands of glass fibers.
 15. The method ofclaim 8 wherein reinforcement comprises glass fibers and/or strands ofglass fibers.
 16. The method of claim 2 wherein the mold element is aheated mold having a tunnel of a desired profile running the length ofthe heated mold in a pultrusion process and wherein the reinforcementcomprises inorganic fibers or strands of fibers and wherein a hot shapeformed in the heated mold is pulled from the heated mold after the shapeat least partially polymerized to form a reinforced thermoplasticinterim product.
 17. The method of claim 16 wherein the inorganic fibersor strands of fibers comprise glass fibers and wherein said sized fibersare preheated to at least 100 degrees C. prior to being coated with themonomer mixture.
 18. The method of claim 2 wherein the monomer mixtureis heated to at least about 100 degrees C. and up to about 190 degreesC.and then is injected into the reinforcement that is inside the molduntil the reinforcement and the mold is fully filled and until thepressure in the mold reaches a desired magnitude.
 19. The method ofclaim 3 wherein the inorganic fibers or strands of fibers comprise glassfibers and wherein said sized fibers are preheated to at least 100degrees C. prior to being coated with the heated monomer mixture. 20.The method of claim 2 wherein the reinforcement comprises choppedinorganic fibers and/or chopped strands of inorganic fibers, and whereinthe reinforcement is fed into the monomer mixture and dispersed into themonomer mixture while being stirred with a mechanical mixer or mixinghead, the temperature of the monomer mixture being above the meltingpoint of the monomer and below the temperature where substantialpolymerization of the monomer will occur producing a moldable compound,at least a portion of the moldable compound is placed into a matchedmetal mold and pressed into a desired shape while heating the moldablecompound and/or desired shape to a temperature within the range of about130 to about 190 degrees C. to polymerize the monomer.
 21. The method ofclaim 20 wherein the inorganic fibers or strands of fibers compriseglass fibers and wherein the glass fibers are preheated to at least 100degrees C. prior to being fed into the monomer mixture.
 22. The methodof claim 1 wherein the coating takes place in a mixing head and theresultant coated reinforcement is injected into a metal mold under apressure of at least about 5 bars.
 23. The method of claim 4 wherein thecoating takes place in a mixing head and the resultant coatedreinforcement is injected into a metal mold under a pressure of at leastabout 5 bars.